Engine Idle Speed Control for Emission Compliance
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Solution Overview
Problem
Heavy duty diesel engine vehicles face challenges in adhering to CARB emission standards during extended idle operation, as current regulations limit idle time to manage NOx and hydrocarbon emissions, necessitating a method to operate beyond mandated idle times without violating emission levels.
Innovation Solution
A method involving an electronic control unit in a vehicle with an internal combustion engine and transmission, which determines idle duration and NOx emissions, limits engine speed to 900 rpm until the parking brake is engaged, allowing continued operation without exceeding emission limits by distinguishing between idle, PTO, and exhaust aftertreatment regeneration modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine operates in idle mode for extended periods, then the vehicle can maintain readiness for immediate operation, but NOx emissions exceed CARB mandated levels
Solution Approach 1:
The system changes the engine operating parameter (speed) from normal idle speed to a limited lower speed (900 rpm or less) when extended idle operation is detected. This parameter change reduces NOx emissions while maintaining the engine in a ready state for immediate operation when the driver needs the vehicle.
2Object-generated harmful factors
If the engine speed is limited to reduce emissions, then NOx emissions decrease, but the engine may not provide sufficient power for immediate operation
Solution Approach 1:
The system dynamically adjusts engine speed based on real-time detection of driver input (accelerator pedal position). When the driver requests power (presses accelerator), the engine immediately transitions from limited speed to normal operating speed, providing full power when needed. This dynamic adjustment maintains both emission compliance during idle and sufficient power availability for operation.
3Power
If the engine operates at normal idle speed, then sufficient power is available for immediate operation, but emissions exceed CARB standards
Solution Approach 1:
The system changes the engine operating parameter (speed) from normal idle speed to a limited lower speed (900 rpm or less) when extended idle operation is detected. This parameter change reduces NOx emissions while maintaining the engine in a ready state for immediate operation when the driver needs the vehicle.
4Duration of action of moving object
If the idle time is extended beyond CARB mandated period, then the vehicle can remain ready for operation, but emission standards are violated
Solution Approach 1:
The system changes the engine operating parameter (speed) to a limited lower speed (900 rpm or less) when the idle operation exceeds a predetermined time period. This allows the engine to continue running for extended periods while maintaining vehicle readiness, but at a reduced emission level that complies with CARB standards.
Data Source
AI summary
A method to operate a vehicle equipped an internal combustion engine and a transmission coupled to drive wheels. The vehicle is equipped with a parking brake and has an electronic control unit with memory and the engine in fluid communication with an exhaust aftertreatment system. The method includes the steps of determining whether the engine is operating in idle mode for a predetermined period of time; determining whether NOx emissions exceed a predetermined level after the predetermined period of time; and limiting the engine speed not to exceed a predetermined engine speed until an operator engages the parking brake and engages an engine ignition switch.